Wearable OLED illumination device

ABSTRACT

Embodiments of the disclosed subject matter may provide a wearable device that includes an organic light emitting diode (OLED) light source to output light. At least one emissive layer of the OLED light source of the wearable device may have a plurality of segments that are independently controllable to output the light at a duty cycle of less than 100%. The OLED light source of the wearable device may be encapsulated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.62/741,201, filed Oct. 4, 2018, and is a continuation of U.S. patentapplication Ser. No. 16/575,444 filed on Sep. 19, 2019, the entirecontents of both are incorporated herein by reference.

FIELD

The present invention relates to wearable OLED (organic light emittingdiode) lighting devices.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting diodes/devices (OLEDs), organic phototransistors, organicphotovoltaic cells, and organic photodetectors. For OLEDs, the organicmaterials may have performance advantages over conventional materials.For example, the wavelength at which an organic emissive layer emitslight may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Alternatively the OLED can be designed to emit white light. Inconventional liquid crystal displays emission from a white backlight isfiltered using absorption filters to produce red, green and blueemission. The same technique can also be used with OLEDs. The white OLEDcan be either a single EML device or a stack structure. Color may bemeasured using CIE coordinates, which are well known to the art.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY

According to an embodiment, an organic light emitting diode/device(OLED) is also provided. The OLED can include an anode, a cathode, andan organic layer, disposed between the anode and the cathode. Accordingto an embodiment, the organic light emitting device is incorporated intoone or more device selected from a consumer product, an electroniccomponent module, and/or a lighting panel.

According to an embodiment, a wearable device may include an organiclight emitting diode (OLED) light source to output light. At least oneemissive layer of the OLED light source may have a plurality of segmentsthat are independently controllable to output the light at a duty cycleof less than 100%, with a periodicity from 1 second to 10 microseconds.The OLED light source of the OLED device may be encapsulated.

The plurality of segments of the wearable device may have the sameemissive layer of the OLED light source, or may have different emissivelayers of the OLED light source.

The OLED light source may include a microcavity to output the light. Thelight output by the OLED light source may be less than 20 nm full widthat half maximum (FWHM). The light output by the OLED light source may be0-250 mW/cm².

The wearable device may include an outcoupling layer coupled to, orintegrated within, the OLED light source. The outcoupling layer may bean internal light extraction layer or an external extraction layer.

One or more of the plurality of segments of the wearable device may bespaced apart from one another. The plurality of segments of the wearabledevice may be independently controllable so that the duty cycle is lessthan 50%.

At least one of the plurality of segments of the wearable device mayoutput the light at a different time than the other segments. The outputof light by the plurality of segments may be less than 50% of theplurality of segments output light at the same time, or less than 25% ofthe segments output light at the same time.

The OLED light source of the wearable device may be disposed on aflexible substrate. The flexible substrate may be without glass. Theflexible substrate may be a metal substrate to reflect light in themicrocavity and to dissipate heat generated by the OLED light source.

The wearable device may include at least one thermally conductive layerto uniformly dissipate heat generated by the OLED light source. Thewearable device may include a fan, and/or at least one fin disposed onthe encapsulation to dissipate heat generated by the OLED light source.

The wearable device may include one or more sensors to detect heatand/or light output by the OLED light source. A processor may becommunicatively coupled to the one or more sensors to control the OLEDlight source based on the detection of at least one of the heat and thelight by the one or more sensors.

The OLED light source of the wearable device may have a plurality ofemitters to emit light having different peak wavelengths of light. TheOLED light source may include at least one down-conversion layer todownconvert light from at least one emissive layer of the OLED lightsource.

The wearable device may include a diffuser disposed over the OLED lightsource to homogenize light from at least one of the plurality ofsegments.

The wearable device may include a patterned substrate to change anoptical path length of at least one of the plurality of segments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows an example of a wearable segmented OLED lighting deviceaccording to an embodiment of the disclosed subject matter.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated byreference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

In some embodiments disclosed herein, emissive layers or materials, suchas emissive layer 135 and emissive layer 220 shown in FIGS. 1-2,respectively, may include quantum dots. An “emissive layer” or “emissivematerial” as disclosed herein may include an organic emissive materialand/or an emissive material that contains quantum dots or equivalentstructures, unless indicated to the contrary explicitly or by contextaccording to the understanding of one of skill in the art. Such anemissive layer may include only a quantum dot material which convertslight emitted by a separate emissive material or other emitter, or itmay also include the separate emissive material or other emitter, or itmay emit light itself directly from the application of an electriccurrent. Similarly, a color altering layer, color filter, upconversion,or downconversion layer or structure may include a material containingquantum dots, though such layer may not be considered an “emissivelayer” as disclosed herein. In general, an “emissive layer” or materialis one that emits an initial light, which may be altered by anotherlayer such as a color filter or other color altering layer that does notitself emit an initial light within the device, but may re-emit alteredlight of a different spectra content based upon initial light emitted bythe emissive layer.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVID. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of electronic component modules (orunits) that can be incorporated into a variety of electronic products orintermediate components. Examples of such electronic products orintermediate components include display screens, lighting devices suchas discrete light source devices or lighting panels, etc. that can beutilized by the end-user product manufacturers. Such electroniccomponent modules can optionally include the driving electronics and/orpower source(s). Devices fabricated in accordance with embodiments ofthe invention can be incorporated into a wide variety of consumerproducts that have one or more of the electronic component modules (orunits) incorporated therein. A consumer product comprising an OLED thatincludes the compound of the present disclosure in the organic layer inthe OLED is disclosed. Such consumer products would include any kind ofproducts that include one or more light source(s) and/or one or more ofsome type of visual displays. Some examples of such consumer productsinclude flat panel displays, computer monitors, medical monitors,televisions, billboards, lights for interior or exterior illuminationand/or signaling, heads-up displays, fully or partially transparentdisplays, flexible displays, laser printers, telephones, mobile phones,tablets, phablets, personal digital assistants (PDAs), wearable devices,laptop computers, digital cameras, camcorders, viewfinders,micro-displays (displays that are less than 2 inches diagonal), 3-Ddisplays, virtual reality or augmented reality displays, vehicles, videowalls comprising multiple displays tiled together, theater or stadiumscreen, and a sign. Various control mechanisms may be used to controldevices fabricated in accordance with the present invention, includingpassive matrix and active matrix. Many of the devices are intended foruse in a temperature range comfortable to humans, such as 18 C to 30 C,and more preferably at room temperature (20-25 C), but could be usedoutside this temperature range, for example, from −40 C to 80 C.

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

In some embodiments, the OLED has one or more characteristics selectedfrom the group consisting of being flexible, being rollable, beingfoldable, being stretchable, and being curved. In some embodiments, theOLED is transparent or semi-transparent. In some embodiments, the OLEDfurther comprises a layer comprising carbon nanotubes.

In some embodiments, the OLED further comprises a layer comprising adelayed fluorescent emitter. In some embodiments, the OLED comprises aRGB pixel arrangement or white plus color filter pixel arrangement. Insome embodiments, the OLED is a mobile device, a hand held device, or awearable device. In some embodiments, the OLED is a display panel havingless than 10 inch diagonal or 50 square inch area. In some embodiments,the OLED is a display panel having at least 10 inch diagonal or 50square inch area. In some embodiments, the OLED is a lighting panel.

In some embodiments of the emissive region, the emissive region furthercomprises a host.

In some embodiments, the compound can be an emissive dopant. In someembodiments, the compound can produce emissions via phosphorescence,fluorescence, thermally activated delayed fluorescence, i.e., TADF (alsoreferred to as E-type delayed fluorescence), triplet-tripletannihilation, or combinations of these processes.

The OLED disclosed herein can be incorporated into one or more of aconsumer product, an electronic component module, and a lighting panel.The organic layer can be an emissive layer and the compound can be anemissive dopant in some embodiments, while the compound can be anon-emissive dopant in other embodiments.

The organic layer can also include a host. In some embodiments, two ormore hosts are preferred. In some embodiments, the hosts used maybe a)bipolar, b) electron transporting, c) hole transporting or d) wide bandgap materials that play little role in charge transport. In someembodiments, the host can include a metal complex. The host can be aninorganic compound.

Copmbination With Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

Various materials may be used for the various emissive and non-emissivelayers and arrangements disclosed herein. Examples of suitable materialsare disclosed in U.S. Patent Application Publication No. 2017/0229663,which is incorporated by reference in its entirety.

Conductivity Dopants:

A charge transport layer can be doped with conductivity dopants tosubstantially alter its density of charge carriers, which will in turnalter its conductivity. The conductivity is increased by generatingcharge carriers in the matrix material, and depending on the type ofdopant, a change in the Fermi level of the semiconductor may also beachieved. Hole-transporting layer can be doped by p-type conductivitydopants and n-type conductivity dopants are used in theelectron-transporting layer.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial.

EBL:

An electron blocking layer (EBL) may be used to reduce the number ofelectrons and/or excitons that leave the emissive layer. The presence ofsuch a blocking layer in a device may result in substantially higherefficiencies, and or longer lifetime, as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the EBLmaterial has a higher LUMO (closer to the vacuum level) and/or highertriplet energy than the emitter closest to the EBL interface. In someembodiments, the EBL material has a higher LUMO (closer to the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the EBL interface. In one aspect, the compound used in EBLcontains the same molecule or the same functional groups used as one ofthe hosts described below.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. Any host material may be used with any dopant so long as thetriplet criteria is satisfied.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies and/or longer lifetime as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the HBLmaterial has a lower HOMO (further from the vacuum level) and or highertriplet energy than the emitter closest to the HBL interface. In someembodiments, the HBL material has a lower HOMO (further from the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the HBL interface.

ETL:

An electron transport layer (ETL) may include a material capable oftransporting electrons. The electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, the CGL plays an essential role in theperformance, which is composed of an n-doped layer and a p-doped layerfor injection of electrons and holes, respectively. Electrons and holesare supplied from the CGL and electrodes. The consumed electrons andholes in the CGL are refilled by the electrons and holes injected fromthe cathode and anode, respectively; then, the bipolar currents reach asteady state gradually. Typical CGL materials include n and pconductivity dopants used in the transport layers.

OLED light sources, as described throughout, may provide source ofillumination for wearable OLED device therapy patches for a plurality ofphotomedicine applications. Some photomedicine applications use narrowspectra (e.g. <20 nm FWHM spectra) at high intensity (e.g. 20,000 cd/m²)at a specific wavelength of light, whereas other applications such asphotobiomodulation use relative broad emission spectra (>50 nm FWHM).OLEDs may be used to provide flexible wearable light sources that mayconform to the human body. The OLED devices disclosed herein may providelight doses without the need for a patient to go to a specific facilityand be irradiated by laser or other bulky light sources. OLEDs may beused to provide large area, flexible light sources for such wearabledevices. Conventional OLEDs arrangements may not be suitable for suchphotomedicine applications because they typically have too wide aspectrum and may not produce a predetermined intensity level, or producetoo much heat to be worn next to the human body

For example, if a conventional OLED device were to produce 20,000 cd/m²operating at 20 cd/A and 5V, the input power would be 500 mW/cm². Thismay not be suitable for a wearable device, as it would lead totemperatures in excess of 50° C.

In embodiments of the disclosed subject matter, OLED devices may producethe desirable spectral characteristics (e.g. less than 20 nm full widthat half maximum (FWHM)) at high luminance (e.g. 20,000 cd/m²) withoutproducing too much heat such that the wearable OLED device may not beuncomfortable to wear. That is, the OLED device may be wearable, as itprovides predetermined output light levels for photomedicine withreduced heat output so as to avoid discomfort of the wearer.Specifically, OLED devices as disclosed herein may be operated for avariety of photomedicine applications without exceeding a temperature of50° C. or a temperature rise of more than 25° C.

Embodiments of the disclosed subject matter provide a wearable OLEDlight source to provide light for photomedicine applications. The OLEDmay be encapsulated by one or more thin films. The one or moreencapsulation layers may be flexible so as to have a radius of curvatureof about 5 cm, and that the OLED light source remains functional whenthe one or more encapsulation layers are flexed. In some embodiments,the OLED may be placed within fabric to make it comfortable. Thewearable OLED device may provide light for hours without inconveniencingand/or causing discomfort to the patient.

According to embodiments of the disclosed subject matter, a wearabledevice may include an organic light emitting diode (OLED) light sourceto output light, which may include the structures shown in FIGS. 1 and2. As shown in FIG. 3 and discussed below, at least one emissive layerof the OLED light source may have a plurality of segments that areindependently controllable to output the light at a duty cycle of lessthan 100%. This implies that the time average output of the device maybe less than that would be provided if all the area of the device wasilluminated continuously. So at any given time, some segments may beilluminated and others not, and which segments are illuminated maychange over time. Each segment would be illuminated with less than 100%duty cycle, with a periodicity from 1 second to 10 microseconds. TheOLED light source of the OLED device may be encapsulated.

Embodiments of the disclosed subject matter may include an OLED thatincludes a microcavity OLED stack. As it may be desirable forphotomedicine applications to use narrow line shapes (e.g. less than 20nm FWHM), a microcavity may be used to produce these narrow line widths.A microcavity may focus the light emission into a direction normal tothe substrate, which may provide increased optical efficiency to thewearable OLED device. This may reduce input power for the OLED lightsource, and may reduce the amount of heat that is generated. That is, anOLED light source of the wearable OLED device may include a microcavityto output the light. The light output by the OLED light source may beless than 20 nm full width at half maximum (FWHM), and may be 0-250mW/cm² of optical output power. For the purposes of this application,the optical output “light” may be visible light (e.g., 400-700 nm), orthe optical output light may extend into the near infra-red, forexample, from 800-1100 nm output.

In some embodiments, the wearable device may include an outcouplinglayer coupled to, or integrated within, the OLED light source. Theoutcoupling layer may be an internal light extraction layer or anexternal extraction layer. The outcoupling layer may be used to increasethe light output. This may lower the power used by the OLED lightsource, which may reduce and/or minimize the heat output from the OLEDlight source. Internal light extraction and/or external light extractionfilms may be incorporated into the OLED light source to maximize lightoutput.

A wearable OLED device may have a predetermined area (e.g., 5 cm×5 cm)as a single pixel. In some embodiments of the disclosed subject matter,the wearable OLED device may include a plurality of segments which maybe individually addressed, such as shown in FIG. 3. The plurality ofsegments of the wearable device may have the same emissive layer of theOLED light source, or may have different emissive layers of the OLEDlight source.

As illuminating the whole wearable OLED device (e.g., at high luminance)at a given time may produce too much heat, embodiments of the disclosedsubject matter may drive one or more segments at the same time. Thesegments that may be driven at the same time may be spaced apart fromeach other, so that heat from each illuminated area may flow tonon-energized regions of the wearable OLED device to promote cooling.

The plurality of segments of the wearable device may be independentlycontrollable so that the duty cycle is less than 50%. For example, ifone third of the plurality of segments of the OLED light source areilluminated (i.e., energized) at any given time, then the wearabledevice may receive one third the heat, thus lowering the operationaltemperature of the wearable OLED device. In some embodiments, the amountof time the wearable OLED device is active may be increased, so that allof the segments would be illuminated over time to provide the desireddosage of light.

At least one of the plurality of segments of the wearable device mayoutput the light at a different time than the other segments. The outputof light by the plurality of segments may be less than 50% of theplurality of segments output light at the same time, or less than 25% ofthe segments output light at the same time.

For example, if the wearable OLED device is to provide one hour of lightexposure to produce a predetermined light dosage, then one third of thesegments of the OLED light source may be energized for an hour. This maybe repeated for an hour for a second set of segments of the OLED lightsource for another one third of the display, and repeated for the finalset of segments of the OLED light source. Alternatively, each set ofsegments of the OLED light source for one third of the wearable OLEDdevice may be energized for one or more minutes, and then the same forthe second set and third set of segments of the OLED light source. Thissequence may be repeated until all of the segments of the OLED lightsource have been illuminated for the predetermined dosage.

In some embodiments, the power used and the heat dissipated by thewearable OLED device may be reduced and/or minimized by pulsing the OLEDlight source. For example, if target molecules for the photomedicineapplication have a response time of about 10 ms, one or more segments ofthe OLED light source may be pulsed using a 50% duty cycle with a 10 msperiod. This may maintain the effectiveness of the light, and the inputpower and heat used by the OLED light source of the wearable OLED devicemay be halved.

The OLED light source may be disposed on thin flexible glass or plastic.In embodiments of the disclosed subject matter, the OLED light source ofthe wearable device may be disposed on a flexible substrate. In someembodiments, the substrate may be flexible so as to have a radius ofcurvature of about 5 cm, and that the OLED light source remainsfunctional when the substrate is flexed.

The flexible substrate may be without glass, as glass may break whenflexed and/or when a user bumps or makes contact with a surface whilewearing the wearable OLED device. The flexible substrate may be a metalsubstrate to reflect light in the microcavity and/or to dissipate heatgenerated by the OLED light source. The metal may act as a thermalconductor such that when one or more segments of the light source areenergized at a given time, the heat may flow uniformly across the OLEDlight source and the wearable OLED device, thus lowering the overalltemperature.

In some embodiments of the disclosed subject matter, one or morethermally conducting layers (e.g., graphene layers) may be included withthe wearable OLED device to spread out and/or dissipate heat generatedby the OLED light source. One side (i.e., a backside) of the wearableOLED device (i.e., a side that is opposite to a side of a surface of thewearable OLED device that contacts the skin) may have a fan, and/or finsdisposed on the surface of the backside. This may increase the backsidesurface area to increase dissipation of heat generated by the OLED lightsource away from the surface of the skin.

In some embodiments of the disclosed subject matter, the wearable OLEDdevice may include a microcavity, which may increase efficiency about1.5 times, an outcoupling film that may provide an increase ofefficiency of about 2 times, and/or segmentation of the OLED lightsource, which may reduce steady-state power by about 4 times. Thecombination of these elements may reduce power consumption by about 12times. This may reduce the initial heat from 500 mW/cm² to 40 mW/cm²,which may not be uncomfortable for a wearable OLED device. In someembodiments, the device may be configured such that it cannot produceheat above a selected threshold, of approximately 50 mW/cm². Forexample, the device may be programmed and/or configured via fixedelectrical wiring to output no more than 40, 50, 100, 200, 250, or 300mW/cm². Some embodiments may achieve this limiting effect by requiringvarious limited duty cycles between one or more segments of the OLEDpanels in the device, as described herein. For example, the wearableOLED device may be configured to require no more than a maximum dutycycle for one or more of the segments, while still allowing the totallight output to be provided at a desired level for any given segmentwhile it is illuminated, as disclosed herein.

In embodiments of the disclosed subject matter, the wearable OLED devicemay include a power supply (e.g., battery), one or more sensors, and aprocessor, such as shown in FIG. 3. The one or more sensors may monitorlight output by the OLED light source, and the processor may determinethe correct light dosage based on the monitored light output. The one ormore sensors may monitor the heat dissipated by the operation of theOLED light source to determine whether the wearable OLED device may beuncomfortable for a user.

A processor, as shown in FIG. 3, may be communicatively coupled to theone or more sensors to control the OLED light source based on thedetection of at least one of the heat and the light by the one or moresensors. The processor may adjust the amount and/or duty cycle of thelight output by the OLED light source to reduce a temperature. That is,OLED light source may be controlled based on measurements made using thetemperature sensors. The processor may be used to control and/or reduceluminance of the OLED light source, and extend application times todeliver a predetermined light dosage while avoiding temperatures thatexceed a predetermine amount.

As shown in FIG. 3, the wearable device may include a wired and/orwireless communications interface. The communications interface may becommunicatively coupled to the processor so that the wearable OLEDdevice may be remotely controlled via control signals received via thecommunications interface.

Different therapies may use different wavelengths of light. Inimplementations of the disclosed subject matter, the OLED light sourceof the wearable device may have a plurality of emitters to emit lighthaving different peak wavelengths of light. The OLED light source mayinclude at least one down-conversion layer to downconvert light from atleast one emissive layer of the OLED light source. The plurality ofemitter may activate one or more drugs for therapeutic applications,and/or provide a wearable OLED device that may activate one or moredrugs (e.g., lower cost drugs). The processor may be programmed to emitlight from a specific emitter for an individual patient, depending onthe therapeutic drug taken by the patient.

In embodiments of the disclosed subject matter, the OLED light sourcesmay be formed in a similar manner to OLED displays, where differentemitters may be deposited or patterned in different regions of thedisplay (e.g., by using organic vapor jet printing (OVJP) or a shadowmask).

Emitters of the same color may be energized at the same time to providebroad area illumination of a single spectrum. In some embodiments of thedisclosed subject matter, a diffuser may be placed over the OLED lightsource to homogenize the light from a specific emitter so the light fromone sub-pixel (per pixel) may provide uniform illumination over thesegment of the OLED light source being energized.

In an embodiment of the disclosed subject matter, the same emitter maybe used, and the substrate may be patterned using lithography. Thepatterned substrate may change an optical path length of at least one ofthe plurality of segments and/or subpixels. This may reduce themanufacturing complexity and/or cost of the OLED light source for thewearable device. That is, broad area lithography may be used to patternthe pixel color, which may be less expensive and/or less complex thatthe use of multiple emitters and an emissive layer patterning process.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

1. A wearable device comprising: an organic light emitting diode (OLED)light source to output light, wherein at least one emissive layer of theOLED light source has a plurality of segments that are independentlycontrollable to output the light, wherein the plurality of segments havethe same emissive layer of the OLED light source, and wherein the OLEDlight source is encapsulated.
 2. The wearable device of claim 1, whereineach of the plurality of segments of the OLED light source emits lightcontinuously over the respective segment.
 3. The wearable device ofclaim 2, wherein each of the plurality of segments has an area of atleast 5 cm×5 cm.
 4. The wearable device of claim 2, wherein each of theplurality of segments has an area of at least 1 cm×1 cm.
 5. (canceled)6. The wearable device of claim 1, wherein the light output by the OLEDlight source is less than 20 nm full width at half maximum (FWHM). 7.The wearable device of claim 1, wherein the light output by the OLEDlight source is selected from the group consisting of: greater than 30nm full width at half maximum (FWHM), greater than 40 nm FWHM, andgreater than 50 nm FWHM. 8.-9. (canceled)
 10. The wearable device ofclaim 1, wherein one or more of the plurality of segments are spacedapart from one another. 11.-15. (canceled)
 16. The wearable device ofclaim 1, wherein the OLED light source has a plurality of emitters toemit light having different peak wavelengths of light.
 17. The wearabledevice of claim 1, wherein the OLED light source includes at least onedown-conversion layer to downconvert light from at least one emissivelayer of the OLED light source. 18.-19. (canceled)
 20. The wearabledevice of claim 1, wherein the at least one emissive layer of the OLEDlight source comprises quantum dots.
 21. A wearable device comprising:an organic light emitting diode (OLED) light source to output light,wherein at least one emissive layer of the OLED light source has aplurality of segments that are independently controllable to output thelight, wherein the plurality of segments have different emissive layersof the OLED light source, and wherein the OLED light source isencapsulated.
 22. The wearable device of claim 21, wherein each of theplurality of segments of the OLED light source emits light continuouslyover the respective segment.
 23. The wearable device of claim 22,wherein each of the plurality of segments has an area of at least 5 cm×5cm.
 24. The wearable device of claim 22, wherein each of the pluralityof segments has an area of at least 1 cm×1 cm.
 25. (canceled)
 26. Thewearable device of claim 21, wherein the light output by the OLED lightsource is less than 20 nm full width at half maximum (FWHM).
 27. Thewearable device of claim 21, wherein the light output by the OLED lightsource is selected from the group consisting of: greater than 30 nm fullwidth at half maximum (FWHM), greater than 40 nm FWHM, and greater than50 nm FWHM. 28.-29. (canceled)
 30. The wearable device of claim 21,wherein one or more of the plurality of segments are spaced apart fromone another. 31.-35. (canceled)
 36. The wearable device of claim 21,wherein the OLED light source has a plurality of emitters to emit lighthaving different peak wavelengths of light.
 37. The wearable device ofclaim 21, wherein the OLED light source includes at least onedown-conversion layer to downconvert light from at least one emissivelayer of the OLED light source. 38.-39. (canceled)
 40. The wearabledevice of claim 21, wherein the at least one emissive layer of the OLEDlight source comprises quantum dots.